Remove Go implementation, promote TypeScript app as canonical

The TypeScript/OOP rewrite has reached full functional parity and is
now the only implementation:

- Delete cmd/, internal/, go.mod, go.sum.
- Promote Dockerfile.node -> Dockerfile and docker-compose.node.yml ->
  docker-compose.yml (service renamed sugarr-node -> sugarr).
- Update README and .gitignore to drop the "two implementations"
  framing and Go-specific entries.

Verified after the rename: tsc --noEmit clean, full test suite
passing (75/75), docker compose build succeeds.

docker-compose.yml

@@ -1,6 +1,8 @@
 services:
   sugarr:
-    build: .
+    build:
+      context: .
+      dockerfile: Dockerfile
     container_name: sugarr
     restart: unless-stopped
     ports:
@@ -23,11 +25,14 @@ services:
       CRON_SCHEDULE: ${CRON_SCHEDULE}
       API_ENABLED: ${API_ENABLED}
       API_PORT: ${API_PORT}
-      RECOMMEND_COUNT: ${RECOMMEND_COUNT}
-      MIN_RATED_MOVIES: ${MIN_RATED_MOVIES}
       SECRET_KEY: ${SECRET_KEY}
+      RECOMMEND_COUNT: ${RECOMMEND_COUNT}
       RECOMMEND_MAX_RETRY: ${RECOMMEND_MAX_RETRY}
-
+      MIN_RATED_MOVIES: ${MIN_RATED_MOVIES}
+      LANGFUSE_PUBLIC_KEY: ${LANGFUSE_PUBLIC_KEY}
+      LANGFUSE_SECRET_KEY: ${LANGFUSE_SECRET_KEY}
+      LANGFUSE_BASE_URL: ${LANGFUSE_BASE_URL}
+      LANGFUSE_PROMPT_CACHE_ENABLED: ${LANGFUSE_PROMPT_CACHE_ENABLED}
     networks:
       - media